This invention relates to an automatic climate control for a vehicle heating, ventilation and air-conditioning (HVAC) system, and more particularly to a method of compensating the control for heating and cooling effects associated with the interior components of the vehicle cabin.
In general, an automatic climate control system regulates the discharge air velocity, temperature and location based on a desired or set temperature and a number of easily measured or estimated parameters such as the outside air temperature, the cabin air temperature, and the solar intensity. In some cases, the parameters are arithmetically combined to form a numerical index or program number from which the discharge air velocity and temperature are determined by table look-up. In other cases, the parameters are used to solve a work or power balance equation for the required heating or cooling effort, and a control algorithm selects one of several possible combinations of discharge air velocity and temperature for satisfying the required effort.
However, the thermal effects associated with the interior components of the vehicle cabin (referred to herein as the deep mass or core components) are typically ignored, particularly in systems that measure the cabin air temperature since the temperature of the deep mass components will eventually be reflected in the measured cabin air temperature. For example, the deep mass components following a heat soak condition will continue to elevate the measured cabin air temperature well after the effects of outside air temperature and solar intensity have been addressed. This indirect method of addressing deep mass temperature effects is obviously reactive in nature, and tends to degrade the cabin air temperature regulation. In systems that do attempt to address deep mass temperature effects, such as the U.S. Pat. No. 5,603,226 to Ishikawa et al., only marginal improvement is achieved because the temperature of the deep mass components is not known. For example, Ishikawa et al. assume that the temperature of the cabin components is equivalent to the temperature of the cabin air, which in actuality is only true after the entire cabin has reached a steady-state temperature. Accordingly, what is needed is an automatic climate control method that directly and accurately accounts for deep mass temperature effects.
The present invention is directed to an improved motor vehicle automatic climate control method in which the heating or cooling influence of the deep mass components of the cabin is accurately determined and used to compensate the climate control for offsetting the thermal effects of the deep mass components on the cabin air temperature. The deep mass temperature is either measured or estimated by modeling, and combined with a measure of the thermal resistance between the deep mass components and the cabin air to determine the heating or cooling power required to offset the deep mass temperature. The heating or cooling power so determined is used by a climate control algorithm to adjust the system air discharge velocity and temperature, directly compensating for the deep mass temperature effects.